1. Field of the Invention
The present invention relates to the management and control of UPnP devices in a home network, and more particularly to an apparatus and method for managing and controlling UPnP devices in a home network over an external Internet network, wherein the external Internet network has the same communication environments as those of the home network so that the UPnP devices in the home network can be managed and controlled from the external Internet network, and a computer-readable storage medium for storing a program for execution thereof.
2. Description of the Prior Art
With the popularization of the Internet, recently, the demand for the Internet in general homes has become widespread. In order to meet this demand, application program developers have developed application programs capable of controlling and managing devices in a home network using home network middleware technologies such as Jini and UPnP, thereby enabling users to manage and control home appliances or security systems in their homes. The UPnP has been proposed as one of the middleware technologies in UPnP Forum, which is a community of two hundred and some companies in various fields, such as home appliances, computers, home automation, mobile devices, etc., founded on Oct. 18, 1999. This Forum has established and published standards of devices and services on the basis of Internet-based communication standards for the purpose of easily and simply constructing networks associated with the devices in homes or offices and controlling the devices over the constructed networks.
A system has been conventionally proposed to control and manage devices in a home network using the UPnP technology. This control/management system comprises a user interface, a UPnP application program interface (referred to hereinafter as API), and a control point. A user can control a specific one of the devices in the home network in such a manner that the user inputs a control command associated with the specific device through the user interface and UPnP API and the control point actually controls the specific device in response to the inputted control command.
However, because the user interface, UPnP API and control point are all present in one system as mentioned above, it is not possible for the user to control the devices in the home network using the system when he/she is beyond the home network. On the other hand, the control point acquires all information necessary for the control of the devices in the home network from advertisement messages sent from the devices. Note that the advertisement messages periodically sent from the devices in the home network can be received only within a limited range. In this regard, as the user is farther from the home network, the probability that the sent advertisement messages will be received is lower.
It is anticipated that the home network will be made of a private network due to depletion of IPv4. In the case where the home network is made of the private network, the advertisement messages from the devices are not sent to the outside of the home network, so the user cannot receive the advertisement messages even when he/she is in the vicinity of the home network. Also, device control commands from the control point cannot be sent to the home network. For this reason, it is impossible for the conventional control/management system to control and manage the UPnP devices in the home network over an external Internet network.
A brief description will hereinafter be given of a conventional method wherein a public network UPnP client controls private network devices. A method for accessing UPnP devices in a private network from an Internet network with a UPnP directory server is disclosed in a reference thesis (Chunglae Cho, Jaemyung Kim and Kwangroh Park, “Accessing UPnP device in Private Networks from Internet with UPnP Directory Server”, Proc. 1st ACIS Annual ICIS'01, Vol. 1, No. 1, pp. 65-70, October 2001). This method is adapted to control UPnP devices with private Internet protocol (IP) addresses in a home network over the Internet by providing on the Internet a UPnP directory server that translates uniform resource locator (URL) information in device descriptions of the UPnP devices by way of a network address translation (NAT) technology and provides the translated information to a client on an external Internet network. The above thesis has also proposed a scheme for extending a simple service discovery protocol (SSDP) to allow the client on the external Internet network to browse UPnP device information on the directory server in a unicast manner. In this method, however, the client on the external Internet network interacts with the directory server only up to a device discovery step. In particular, communication can be conducted between the external client and the UPnP directory server by translating a network address using the NAT and modifying (extending) the UPnP SSDP.
On the other hand, an apparatus and method for bridging between an HAVi sub-network and a UPnP sub-network are shown in European Patent No. EP 1 058 422 A1. In this patent, an HAVi device controls a UPnP device through the use of a sub-network bridging unit that declares the UPnP device an HAVi DCM and a UPnP service an HAVi FCM, respectively.
Korean Patent Application No. 1999-33936 discloses a method for connection between a private network and a global network by a router. In this method, the router is adapted to connect the private network and the global network with each other using the NAT. A public network host can access a private network host by means of the NAT.
However, the above-mentioned preceding patents disclose various methods for accessing and controlling UPnP devices, but show no method for controlling and managing UPnP devices in a home network from an external Internet network. Although the above reference thesis shows a method for controlling and managing UPnP devices in a home network over an external Internet network, an external client interacts with a directory server only up to a device discovery step. In particular, this method has the trouble of having to translate URL information using the NAT and modify (extend in this specification) a UPnP SSDP. This method is further disadvantageous in that the external Internet network does not have the same communication environments as those of the home network.